Electronic label

ABSTRACT

One characteristic of electronic labels is that they can be read and written on without electrical contact through the communication coil ( 1 ). The reading head is then positioned at some distance and communicates with the label through electromagnetic waves.  
     When these labels are placed on metallic objects, reading becomes difficult even impossible because of the dispersion of the waves in the object.  
     To overcome this drawback, the invention proposes the adding of an electromagnetic conductive element ( 3, 3′ ) to the coil ( 1 ) in order to insulate it ( 1 ) and enhance the reception quality.

[0001] This invention concerns the domain of electronic labels, moreparticularly labels designed to be placed on a metallic object.

[0002] By electronic label one understands, a set having at least onesupport, an antenna and an electronic chip. This set can include severalantennas or several chips according to the requirements. One finds themin the form of a button, in chip cards and even in luggage labels.Thanks to their antennas, they can communicate with a remote reader. Theantenna serves not only as a means of communication, but also to producethe necessary energy to feed the electronic chip.

[0003] Some of these labels do not include electronic chips but passivecomponents such as resistors or fuses. They are used to identifyobjects, for example in an anti-theft application.

[0004] According to the embodiments, the antenna is fitted to theflexible support or directly engraved or cut on this same support.

[0005] There are a lot of chips, which differ because of theirfunctionalities, for example certain ones allow only the reading ofinformation while others allow memorization and modification of theirmemory. The latter are used among other reasons for electronic cash cardapplications, which obviously need, a read/write feature in order tomodify the contents according to the consumption of the user.

[0006] Another important application field is identification of theobjects. In fact, in an automatic manufacturing cycle, it isindispensable than the automaton knows exactly which component it is infront of. The tendency in this kind of use is to replace the “bar-code”labels by labels equipped with an electronic chip. This not only allowsidentification of the object but also inversely allows the object toremember the manufacturing steps that it has been through.

[0007] Nevertheless, the problem that this kind of using comes from thenature of the object. In fact, these labels work according to theprinciple of a link by a magnetic field, they are disturbed by theproximity of a metallic mass absorbing the waves that allowcommunication.

[0008] In order to overcome this drawback, it is necessary to bring thelabel reader nearer to a distance of some millimeters to restore thecommunication.

[0009] In certain applications, one easily imagines that this distanceconstraint can present major drawbacks for objects having an angularoutline for example.

[0010] There are solutions in which such a label comprises an electricconductive layer. There is for example the case in the document U.S.Pat. No. 5,920,290 where one of the executions describes a set of anantenna and a conductive sheet to create a resonant circuit. The aim ofsuch a sheet, whose structure can also be obtained as well by metalcoating as by carbon supplying, shows that the aim and the means toachieve this are far from the object of the present application.

[0011] Other documents describe the use of a conductive layer inside anelectronic label that makes the necessary tracks for the routing ofelectric signals. There is the case in document WO00/03354 that is aboutthe manufacturing of a TAG by assembling different layers. No mention ofa magnetic reflector function is present in relation to these conductivelayers.

[0012] Document WO00/25263 describes a protection method of atransponder against discharges of static electricity. This protection isachieved with a sheet of semiconductor material placed on a section ofthe coil. With its structure, it forms a diode limiter between the turnsof the coil. Otherwise said, this sheet constitutes a filter in chargedto eliminate parasitic signals created by static discharge orelectromagnetic disturbances which could harm the good work of thetransponder. Such a semiconductor sheet cannot thus in any case bemagneto reflective because its role is limited, on the contrary, toreducing or to absorbing undesirable electromagnetic signals. By theway, this document does not mention electromagnetic field reflection bya component of the transponder or possible problems caused by thesupport where this transponder would be applied.

[0013] The aim of this invention is to propose an electronic label whosereading distance is distinctly improved in order to allow a lessaccurate placement of the readout head.

[0014] This aim is achieved by an electronic label having at least oneelectronic element and a coil, characterized in that the coil comprises,on one of its sides, a magneto reflective element.

[0015] By electronic element one understands either an electronic chip,or a passive component such as a fuse or a resistor.

[0016] This element is placed on the opposite side of the readertransmission side. With the presence of this element, the magnetic fieldis let say reflected against the reader instead of being dispersed inthe metallic object.

[0017] The position and shape of the element play an important role.

[0018] In a variant of the invention, the magneto reflective element isdisposed in the form of a sheet sensibly at the same size than the coil.The distance between the coil and the sheet is determined to obtain theoptimal researched characteristics.

[0019] According to another embodiment, the sheet exceeds slightly thesurface of the coil, creating an edge effect, which allows the magneticfield to be captured and thus increases the acceptable reading distance.

[0020] The testing has shown that the shape and distance of the sheetare determined in function of the characteristics of the label, inparticular of the transmission frequency. Thanks to this magnetic sheet,it is possible to read a label placed on a metallic part at anacceptable distance for this kind of application.

[0021] This sheet can have non-planar geometric shapes, for example itcan go over the rim of the coil. According to the requirements, thissheet can include openings whose shape is determined by the researchedmagnetic characteristics.

[0022] This sheet can be directly placed under the coil or at apredetermined distance, for example by means of an insulating layer.

[0023] The invention will be better understood thanks to the followingdetailed description referring to the attached drawings given as anon-limiting example:

[0024]FIG. 1 represents an electronic label with a protection sheetaccording to the invention,

[0025]FIG. 2 represents an electronic label with a magnetic protectionring

[0026] In FIG. 1, representing a section of an electronic label, one candistinguish the schematized coil 1 as well as the electronic chip 2.Note that although this chip is situated inside the coil, it also can besituated outside the surface defined by the coil.

[0027] Under the coil 1, is placed the magneto reflective sheet 3separated by an insulating layer 4 and defining the distance between thecoil and the magnetic sheet. The presence of this insulating layer isnot necessary to obtain the desired effect; the magneto reflective sheetcan be directly applied onto the coil.

[0028] This sheet 3 is placed on the opposite side of the reader(schematized by field lines F), that is to say on the application sideof the label on the object having metallic characteristics.

[0029] This set can be embedded in a resin or encapsulated between twoprotection sheets. The shape of this label can be any as a card, abutton, or mounted on a flexible support.

[0030] According to a variant of the invention, shown in FIG. 2, themagneto reflective sheet can have other shapes to be placed only on theperiphery of the coil. This element can be made in the form of a ferritering 3′ for example or made as a magnetically conductive mechanicallystamped sheet whose center would contain the coil.

[0031] The effect of magnetic flux concentrator also operates if themagnetic element is not placed under the coil but on its nearbyperiphery. For this purpose, it is useful to note that it is notnecessary that the magnetic element surrounds the whole periphery of thecoil. Positive results have been observed using such an element on onlyone section of the periphery of the coil.

[0032] This embodiment does not exclude the use of a magnetic sheet suchas the one previously described placed under the coil in addition to theperipheral element. Furthermore it is possible to make a single piecewith these two parts.

1. Electronic label comprising at least one electronic element (2) and acoil (1), characterized in that the coil (1) includes at least onemagneto reflective element constituted by an electromagnetic conductiveelement (3, 3′) independent of the set formed by the electroniccomponent (2) and the coil (1).
 2. Electronic label according to claim1, characterized in that the magneto reflective element (3, 3′) coversall or part of the surface of the coil (1).
 3. Electronic labelaccording to claim 1, characterized in that the magneto reflectiveelement (3, 3′) is slightly larger than the surface of the coil (1). 4.Electronic label according to claims 1 to 3, characterized in that themagneto reflective element (3, 3′) comprises three-dimensional shapes.5. Electronic label according to claims 1 to 4, characterized in thatthe magneto reflective element (3, 3′) comprises one or several openingson its surface.
 6. Electronic label according to claim 1, characterizedin that a first magneto reflective element (3, 3′) is situated on all orpart of the periphery of the coil (1).
 7. Electronic label according toclaim 6, characterized in that the magneto reflective element (3, 3′)comprises a second part which covers all or part of the surface of thecoil (1).
 8. Electronic label according to claim 7, characterized inthat the second part of the magneto reflective element (3, 3′) isslightly larger than the surface of the coil (1).
 9. Electronic labelaccording to claims 7 and 8, characterized in that the second part ofthe magneto reflective element (3, 3′) comprises three-dimensionalshapes.
 10. Electronic label according to claims 7 to 9, characterizedin that the second part of the magneto reflective element (3, 3′)comprises one or several openings on its surface.
 11. Electronic labelaccording to claims 7 to 10, characterized in that the first and secondparts of the magneto reflective element (3, 3′) are made in a singlepiece.